The present invention relates to an image processing apparatus, and more particularly, to an image processing apparatus capable of performing a compressed code decoding processing or image data encoding processing in time division by multiple processing.
Conventionally, G3 facsimile apparatuses have been widely used in offices and have become a necessary item in office automation. Its functions have been expanded, and, a user can choose a desired apparatus from a wide price range. The transmission rate has been also increased and an apparatus in which transmission rate is over 20 kbps has been developed.
Furthermore, ISDN, a digital communication network, has started to replace telephone communication lines and G4 facsimile apparatuses capable of connecting to an ISDN are gradually increasing. Features of G4 facsimile apparatuses include a high resolution of 400 dpi and the capability of high-speed communication at 64 kbps.
On the other hand, it became possible to use ordinary paper for a facsimile apparatus and a number of facsimile apparatuses using a high-resolution printer, such as a laser printer or ink-jet printer, have been developed. Accordingly, a high-quality image can be transmitted at a high speed due to the high-speed communication capability of G4 apparatuses and the output of the laser printer at high resolution.
Since a laser printer is a type of a page printer which outputs one page at a predetermined rate, an image needs to be output in real time. Accordingly, a page buffer which stores raw image data of one page is required depending on the rate of the image data processing such as compressed code decoding processing. Furthermore, an apparatus which is devoid of a page buffer for raw image data has been developed by adopting a unit which processes the compressed code decoding processing in real time.
Furthermore, users' demand in rapid access has been increased, resulting in development of an apparatus capable of reading 30 pages (3.85 mm/line) per minute. Accordingly, facsimile transmission can be executed by quick response and it has become an attractive function for the users.
A function such as multi-access or dual access has been developed thereby providing better operation for the users. In a facsimile connected to the ISDN, the "multi-access" function refers to the following functions:
(1) Transmission can be carried out while a reception is in progress; and PA1 (2) Reception can be carried out while a transmission is in progress. The "dual-access" function refers to the following functions:
(1) Transmission reservation can be carried out while a transmission or reception is in progress; and PA2 (2) Copying or transmission reservation can be carried out during a memory transmission.
However, the facsimile apparatus having a printer such as a laser beam printer, a page printer, performs encoding into a compressed code or decoding the encoded compressed-code on a plurality of pages simultaneously. These processings need to be done rapidly, resulting in complication in the construction or control, and an increase in cost.